matlab与C++以.mat文件方式进行数据相互流动

年前，放假回家之前，使用了C++与matlab之间的数据的互动的一个实验，感觉效果挺好。初步达到了目的，所以整理下来方便大家使用。减少大家编程学习的时间。
希望对你们有用。

#include "mat.h"

void example8()
{
　　 const char **fnames;       /* pointers to field names */
    const mwSize *dims;
    mxArray    *tmp, *fout;
    char       *pdata=NULL;
    int        i_field, nfields;
    mxClassID  *classIDflags;
    mwIndex    j_struct;
    mwSize     NumStructRecords;
    mwSize     ndim;

	MATFile *pMF;
	mxArray *pRoad, *pOut;
	int status;
	const char *file = "ContourRoadResults_AfterWidthEtcCorrect_4_ZY.mat";

	printf("Opening file %s...\n\n", file);
	pMF = matOpen(file, "u");
	pRoad=matGetVariable(pMF, "ContourRoadResults");

    /* get input arguments */
    nfields = mxGetNumberOfFields(pRoad);
    NumStructRecords = mxGetNumberOfElements(pRoad);
    /* allocate memory  for storing classIDflags */
    classIDflags = (mxClassID*) mxCalloc(nfields, sizeof(mxClassID));

    /* check empty field, proper data type, and data type consistency;
     * and get classID for each field. */
    for(i_field=0; i_field<nfields; i_field++)
	{
        for(j_struct = 0; j_struct < NumStructRecords; j_struct++)
		{
            tmp = mxGetFieldByNumber(pRoad, j_struct, i_field);
            if(tmp == NULL)
			{
                printf("%s%d\t%s%d\n", "FIELD: ", i_field+1, "STRUCT INDEX :", j_struct+1);
                //mexErrMsgIdAndTxt( "MATLAB:phonebook:fieldEmpty", "Above field is empty!");
            }

            if(j_struct==0)
			{
                if( (!mxIsChar(tmp) && !mxIsNumeric(tmp)) || mxIsSparse(tmp)) {
                    printf("%s%d\t%s%d\n", "FIELD: ", i_field+1, "STRUCT INDEX :", j_struct+1);
                   // mexErrMsgIdAndTxt( "MATLAB:phonebook:invalidField",
                   //         "Above field must have either string or numeric non-sparse data.");
                }
                classIDflags[i_field]=mxGetClassID(tmp);
            }
			else
			{
                if (mxGetClassID(tmp) != classIDflags[i_field])
				{
                    printf("%s%d\t%s%d\n", "FIELD: ", i_field+1, "STRUCT INDEX :", j_struct+1);
                    //mexErrMsgIdAndTxt( "MATLAB:phonebook:invalidFieldType",
                    //        "Inconsistent data type in above field!");
                } else if(!mxIsChar(tmp) &&
                        ((mxIsComplex(tmp) || mxGetNumberOfElements(tmp)!=1))){
                    printf("%s%d\t%s%d\n", "FIELD: ", i_field+1, "STRUCT INDEX :", j_struct+1);
                    //mexErrMsgIdAndTxt( "MATLAB:phonebook:fieldNotRealScalar",
                    //        "Numeric data in above field must be scalar and noncomplex!");
                }
            }
        }
    }

    /* allocate memory  for storing pointers */
    fnames = (const char **)mxCalloc(nfields, sizeof(*fnames));
    /* get field name pointers */
    for (i_field=0; i_field< nfields; i_field++){
        fnames[i_field] = (char*)mxGetFieldNameByNumber(pRoad,i_field);
    }

    /* create a 1x1 struct matrix for output  */
    pOut = mxCreateStructMatrix(1,1,nfields, fnames);
    mxFree((void *)fnames);
    ndim = mxGetNumberOfDimensions(pRoad);
    dims = mxGetDimensions(pRoad);
    for(i_field=0; i_field<nfields; i_field++) {
        /* create cell/numeric array */
        if(classIDflags[i_field] == mxCHAR_CLASS) {
            fout = mxCreateCellArray(ndim, dims);
        }else {
            fout = mxCreateNumericArray(ndim, dims, classIDflags[i_field], mxREAL);
            pdata = (char*)mxGetData(fout);
        }
        /* copy data from input structure array */
        for (j_struct=0; j_struct<NumStructRecords; j_struct++) {
            tmp = mxGetFieldByNumber(pRoad,j_struct,i_field);
            if( mxIsChar(tmp)) {
                mxSetCell(fout, j_struct, mxDuplicateArray(tmp));
            }else {
                mwSize     sizebuf;
                sizebuf = mxGetElementSize(tmp);
                memcpy(pdata, mxGetData(tmp), sizebuf);
                pdata += sizebuf;
            }
        }
        /* set each field in output structure */
        mxSetFieldByNumber(pOut, 0, i_field, fout);
    }

	matPutVariable(pMF, "OutputResult_Convert",pOut);
    mxFree(classIDflags);
	if (matClose(pMF) != 0) {
		printf("Error closing file %s\n",file);
		return;
	}
	printf("Done\n");
	return;
}

项目需要进行事先的C++ MEX混合编程的标准配置，再此不再赘述。要提醒的是，需要加入的头文件是#include "mat.h"。另外，具体的其他函数，请参照matlab的 MAT文件的读写的相关内容。

这个帮助对相关函数说明比较详细，参照相关的demo文件，你就能很快上手。

祝愿能解决你的问题！